The objective of this proposal is to examine the role of glycoprotein oligosaccharides as information-bearing macromolecules involved in inter- and intracellular communication. This project has three phases, the first of which is to define the structure of the oligosaccharides present on the high uptake form of human Beta-glucuronidase, human Beta-hexosaminidases A and B, an IgD myeloma protein, the galactose-specific carbohydrate binding protein (Gal-CBP) of human hepatocytes, and other vertebrate carbohydrate-binding proteins (CBPs) detected by affinity labeling. A method for microsequencing utilizing the introduction of fluorescent probes onto oligosaccharides and separation by high performance liquid chromatography is presented for use in such studies. Altered exposure of oligosaccharides following ligand binding by monoclonal IgG and IgM, and haptoglobin will also be examined as a potential source of specificity. The second phase will consist of the synthesis of photoactivatable, 125I-labeled oligosaccharide affinity probes and their utilization to identify, isolate, and examine vertebrate CBPs. The third phase will involve detailed studies of the CBPs thus identified and isolated. The specificity of CBPs will be defined by carrying out binding studies with glycoproteins and oligosaccharides of known structure. The behavior of the CBP in intact cells will be examined using the glycoproteins and oligosaccharides as well as by affinity labeling which will permit direct examination of the CBP in the cell. CBPs will be incorporated into liposomes to examine their potential role in cell-cell recognition and to introduce purified CBP into other cells such as fibroblasts by fusion. Introduction of the receptor into cells will make it possible to determine the components involved in endocytosis by CBP.